What can be done to save Hayle Beach?

In my previous article I stated that Hayle Beach and the dunes of Harvey’s Towans hadn’t stabilised yet. In fact, over the next few months we will see spring tides reach up to 7.3m above chart datum. These tides will unfortunately cause more erosion of the dunes. So what can be done to stop it?

In the short-term, there are a number of options to prevent anymore erosion. Rock armour emplaced at the toe of the dunes would prevent waves reaching them and undermining them. A small section of Hayle Beach has seen this type of scheme being used to provide a footing for a beach access slope. These rocks would prevent the dunes retreating further inland and would offer protection to the chalets built on the Towans.

Another option would be to replenish Hayle Beach with sand and install groynes which would prevent sand from being lost. This scheme would dissipate wave energy (helping to reduce the strong flood tide flows in the area), offer some protection to the dunes and would also prevent the Wave Hub cable from being reexposed.

In the long-term Hayle Beach has to be sustainable. At present no sediment is being supplied to the beach except from the dunes. There a re a number of reasons for this. Firstly, sediment transport (littoral drift) directions diverge at Black Cliff. Sand on Hayle Beach is transported in a westerly direction, straight into the harbour. From Black Cliff to Godrevy Point the direction is to the east. Secondly, the channel has curved to the east. The strong flows that constantly run through the channel act as a physical barrier toany sand being brought from offshore, in longshore currents and from Porth Kidney Sands. This effectively puts Hayle Beach in a shadow zone. Any sediment that reaches the channel is quickly sent to the area of beach in front of Cove Cafe, where a marked d ifference in beach height is seen.

Sand is being constantly lost from the beach to the harbour on the flood tides and to the Black Cliff area and o ffshore on the ebb tide.

The key to making Hayle Beach sustainable is to have a straight channel which is orientated in a northwards direction from Chapel Anjou Point. This reduces the shadow zone dramatically and allows sand to be brought to the beach. In essence it allows the source and terminal areas of sediment transport to be connected again.

Anne-Marie Rance, Bsc (hons) Geosciences.

Next issue I will discuss how sluicing would help to achieve sustainability.